Often wellbores, whether completed open-hole or with perforated casing, produce excess sand. In order to control the flow of particles into the wellbore, well screens are commonly positioned adjacent to the perforated or unlined portion of the wellbore. Typical sand control systems include stand-alone screens (SAS), open-hole gravel packs (OHGP), and expandable sand screens (ESS).
SAS systems include a relatively large annulus formed between the wall of the wellbore and the screen. The systems commonly experience localized screen plugging resulting in increased flow velocity through the screen causing erosion and ultimate failure of the system.
OHGP systems are similar to SAS systems with the inclusion of a proppant placed in the annulus between the screen and the wellbore wall forming a “gravel pack.” Common drawbacks of these systems are the cost and complexity of providing the gravel pack and bridging that results in poor gravel packs.
In conventional ESS systems the entire sand screen assembly is expanded to the wall of the wellbore, minimizing the annulus between the outside diameter of the screen and the inside diameter of the wellbore. These systems address the cost and complexity of placing a gravel pack, however, they introduce cost and complexity of expanding the screen assembly. A significant drawback of conventional ESS systems is that the internal base pipe that underlies the screen assembly is expanded resulting in a reduced collapse strength that renders the systems as unsuitable for wells with large overburdens.
Therefore, it is a desire to provide an expandable well screen that addresses drawbacks of the current and prior sand control completion systems. It is a further desire to provide an expandable well screen that minimizes the annulus between the screen and the wellbore wall. It is still a further desire to provide an expandable well screen that includes an expandable screen with a stable base pipe that maintains a substantially constant geometry before and after expansion of the screen.